1. Field of the Invention
This invention relates to certain novel mixed oxides of rhenium useful in electrical elements.
2. Prior Art
Few mixed oxides of rhenium are known. Understandably, these have involved the combination of the small, highly charged rhenium ion with large basic cations. Thus, with the large barium ion, compositions Ba.sub.2 MReO.sub.6 are formed. These have a perovskite structure with the large Ba.sup..sup.+2 ions in 12-fold coordination while Re.sup..sup.+5 or Re.sup..sup.+6 shares 6-fold sites with the M.sup..sup.+3 or M.sup..sup.+2 cation. Another example is KReO.sub.4 having the scheelite structure with the large K.sup.+ ions in 8-fold coordination; see J. C. Morrow, Acta. Cryst. 13, 443-445 (1960). Still another example utilizes the relatively large Cd.sup..sup.+2 ion in 8-fold sites of the pyrochlore structure to form the electrically conductive Cd.sub.2 Re.sub.2 O.sub.7 (Donohue et al., Inorg. Chem. 4, 1152-53 (1965).